LXR linux/drivers/clk/tegra/cvb.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Utility functions for parsing Tegra CVB voltage tables
   4 *
   5 * Copyright (C) 2012-2019 NVIDIA Corporation.  All rights reserved.
   6 */
   7#include <linux/err.h>
   8#include <linux/kernel.h>
   9#include <linux/pm_opp.h>
  10
  11#include "cvb.h"
  12
  13/* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
  14static inline int get_cvb_voltage(int speedo, int s_scale,
  15                                  const struct cvb_coefficients *cvb)
  16{
  17        int mv;
  18
  19        /* apply only speedo scale: output mv = cvb_mv * v_scale */
  20        mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
  21        mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
  22        return mv;
  23}
  24
  25static int round_cvb_voltage(int mv, int v_scale,
  26                             const struct rail_alignment *align)
  27{
  28        /* combined: apply voltage scale and round to cvb alignment step */
  29        int uv;
  30        int step = (align->step_uv ? : 1000) * v_scale;
  31        int offset = align->offset_uv * v_scale;
  32
  33        uv = max(mv * 1000, offset) - offset;
  34        uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
  35        return uv / 1000;
  36}
  37
  38enum {
  39        DOWN,
  40        UP
  41};
  42
  43static int round_voltage(int mv, const struct rail_alignment *align, int up)
  44{
  45        if (align->step_uv) {
  46                int uv;
  47
  48                uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
  49                uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
  50                return (uv * align->step_uv + align->offset_uv) / 1000;
  51        }
  52        return mv;
  53}
  54
  55static int build_opp_table(struct device *dev, const struct cvb_table *table,
  56                           struct rail_alignment *align,
  57                           int speedo_value, unsigned long max_freq)
  58{
  59        int i, ret, dfll_mv, min_mv, max_mv;
  60
  61        min_mv = round_voltage(table->min_millivolts, align, UP);
  62        max_mv = round_voltage(table->max_millivolts, align, DOWN);
  63
  64        for (i = 0; i < MAX_DVFS_FREQS; i++) {
  65                const struct cvb_table_freq_entry *entry = &table->entries[i];
  66
  67                if (!entry->freq || (entry->freq > max_freq))
  68                        break;
  69
  70                dfll_mv = get_cvb_voltage(speedo_value, table->speedo_scale,
  71                                          &entry->coefficients);
  72                dfll_mv = round_cvb_voltage(dfll_mv, table->voltage_scale,
  73                                            align);
  74                dfll_mv = clamp(dfll_mv, min_mv, max_mv);
  75
  76                ret = dev_pm_opp_add(dev, entry->freq, dfll_mv * 1000);
  77                if (ret)
  78                        return ret;
  79        }
  80
  81        return 0;
  82}
  83
  84/**
  85 * tegra_cvb_add_opp_table - build OPP table from Tegra CVB tables
  86 * @dev: the struct device * for which the OPP table is built
  87 * @tables: array of CVB tables
  88 * @count: size of the previously mentioned array
  89 * @align: parameters of the regulator step and offset
  90 * @process_id: process id of the HW module
  91 * @speedo_id: speedo id of the HW module
  92 * @speedo_value: speedo value of the HW module
  93 * @max_freq: highest safe clock rate
  94 *
  95 * On Tegra, a CVB table encodes the relationship between operating voltage
  96 * and safe maximal frequency for a given module (e.g. GPU or CPU). This
  97 * function calculates the optimal voltage-frequency operating points
  98 * for the given arguments and exports them via the OPP library for the
  99 * given @dev. Returns a pointer to the struct cvb_table that matched
 100 * or an ERR_PTR on failure.
 101 */
 102const struct cvb_table *
 103tegra_cvb_add_opp_table(struct device *dev, const struct cvb_table *tables,
 104                        size_t count, struct rail_alignment *align,
 105                        int process_id, int speedo_id, int speedo_value,
 106                        unsigned long max_freq)
 107{
 108        size_t i;
 109        int ret;
 110
 111        for (i = 0; i < count; i++) {
 112                const struct cvb_table *table = &tables[i];
 113
 114                if (table->speedo_id != -1 && table->speedo_id != speedo_id)
 115                        continue;
 116
 117                if (table->process_id != -1 && table->process_id != process_id)
 118                        continue;
 119
 120                ret = build_opp_table(dev, table, align, speedo_value,
 121                                      max_freq);
 122                return ret ? ERR_PTR(ret) : table;
 123        }
 124
 125        return ERR_PTR(-EINVAL);
 126}
 127
 128void tegra_cvb_remove_opp_table(struct device *dev,
 129                                const struct cvb_table *table,
 130                                unsigned long max_freq)
 131{
 132        unsigned int i;
 133
 134        for (i = 0; i < MAX_DVFS_FREQS; i++) {
 135                const struct cvb_table_freq_entry *entry = &table->entries[i];
 136
 137                if (!entry->freq || (entry->freq > max_freq))
 138                        break;
 139
 140                dev_pm_opp_remove(dev, entry->freq);
 141        }
 142}
 143